High above No.10 Harley Street, London, in the squishy-cushioned, heavy-draped offices of holistic skin care specialist Claudia Louch, a familiar prickle of panic spreads across the back of my skull.

"If you can just take off your make-up for a photo…" the assistant repeats. I’d forgotten about this bit—the picture required at every appointment to document any progress we make with my stubbornly—chronically—blotchy complexion. But today, I dashed from my office and left my makeup bag there. For most people—those who, unlike me, are gloriously free from acne—it’s like getting to the airport without your passport. Or leaving the house without your skirt.

So I tell the poor assistant that, no, I won’t be taking off my makeup. We’ll just have to skip the picture. She gives me a small nod: the pro’s way of dealing with the slightly rude. Or maybe it was sympathy. Maybe she gets that merely talking about the thing that every day you try to hide—with makeup, with hairstyles, with a well-placed hand in front of your face—is stressful. And the thought of smearing away that protective layer and walking back to your office, bare-faced, for strangers and colleagues to see, to judge—well, that’s plain terrifying.

But of course, this is the time of year you wish barefaced wasn’t such a scary concept. You wish you weren’t the only woman on the beach wearing foundation. And so I came to Louch partly because of that—a modest desire to pull off that natural sun-kissed look like everyone else. But mostly because my dodgy complexion is complemented by an equally dodgy stomach (bloating, painfully infrequent toilet trips, sexy stuff like that) and Louch works in a way that few other skin aestheticians on Harley Street—London’s Mecca of perfect complexions—do. Instead of peeling or injecting or lasering, Louch—who has a degree in phytomedicine (plant-based medicine) and a masters in conventional drug discovery—treats from the inside out. She sees skin disorders (like rosacea, eczema, or acne) as symptomatic of other issues in the body—primarily the gut.

It’s hardly an original perspective. I’ve seen enough nutritionists and herbalists and goodness-knows-who-else to have heard the gut-skin theories before. Even in bonafide scientific research, the link between skin and stomach has been noted. Most recently, a 2008 study of 13,000 acne sufferers found that they were more likely to suffer things like constipation and bloating. But now, science is telling us why. And it’s all to do with your bacteria.

Insider Secrets
If you’ve missed the buzz, then let me tell you that gut microbiota (the community of microorganisms that inhabit your gastrointestinal tract) are the current talk of the medical town. “More than 80 percent of the body’s immunity is located in the gut, so it’s hardly surprising that what’s living in there is going to have a big impact on our overall health," says Grace Liu, a pharmacist and nutritional scientist. "But it’s only over the past five years or so that we’ve developed the ability to sequence gut microbiota (i.e., to fully understand its structure) so we can study it the way we were studying DNA 20 years ago. It’s like a black box that’s been opened."

The contents of the box tells us that these microbes may have an effect on everything from our body fat to our mental health, and yes, our complexions. "This really is a new frontier," says Whitney Bowe, M.D., a dermatologist based in downtown New York City who has pioneered work into the link between the gut, skin, and brain. "The research in the gut’s effect on skin is somewhat behind other areas, but nobody is arguing against connection anymore."

To understand the connection, we need to understand the premise of a healthy gut. "First, you need a good vartiation in bacteria," says Liu. "Secondly, that bacteria should be well balanced, which means you have more of the good guys than the bad." In support of this theory, a significant Russian study found that 54 percent of acne patients have marked alterations to the intestinal microflora. "We’re not saying that all acne is caused directly by an imbalance in gut flora—it’s merely a piece in the jigsaw," says Bowe. "But it’s a significant piece."

Why? Well, predictably, it’s complicated but the overriding paradigm goes something like this: “Essentially, good bacteria strengthens the lining of the gut," says Liu. “We know that low levels of this good bacteria and higher levels of pathogens like bad bacteria, fungi [yeast], or viruses can increase gut permeability, enlarging the microscopic gaps between the gut cells. Minute microbial toxins are then able to pass through these gaps into your system. Your immune system then detects these invaders, overreacts, and causes inflammation." And acne, in case you hadn’t guessed, is an inflammatory condition.

"There are inflammatory markers in the skin called cytokines," says Farage Al-Ghazzewi, Ph.D., a microbial health specialist based in Glasgow, Scotland. "We know that these are involved in the formation of acne lesions and that their numbers are higher in people with acne."

So heal the gut, and you’ll eventually heal the skin. Which is why the first thing Louch did during our initial consultation was order a urine analysis to see whether the bacteria in my gut was out of whack.

The Perfect Storm
“You have a yeast overgrowth,” she says, looking at my results. “Which inevitably means you won’t have as much good bacteria as you should.” And it seems I’m just a symptom of a modern epidemic. “The state of our guts has a lot to do with the 21st-century diet, “ says Stanford University professor Justin Sonnenburg, co-author of The Good Gut. "Sugary, processed foods do nothing to feed the healthy gut flora.

"The other major factor is antibiotics. Most of us have taken them at least sporadically since childhood. But antibiotics don’t discriminate between good and bad—they wipe out everything. When they wipe out the good bacteria, pathogens can grow and take up their space." If you’ve ever had a yeast infection after a course of antibiotics, then you’ve experienced this in action.

Louch says a one-week course of antibiotics can affect the gut microbiota for three years. So as a kid who was born with colic, raised on dessert, and spent her twenties cashing in prescriptions for bladder infections, I was basically a gastro-disaster-in-the-making.

She prescribes me an antifungal supplement to kill of the bad stuff and a probiotic to build up the good. Probiotics’ ability to improve acne symptoms has become well established. "Various probiotics—particularly Lactobacillus casei and Lactobacillus plantarum [which you can get over the counter], have been shown to regulate the production of those inflammatory cytokines," says Al-Ghazzewi.

In fact, a 2010 study published in the journal Nutrition found that giving acne patients the probiotic strain lactobacillus in the form of a fermented milk drink lead to a reduction in acne lesions. And get this—last year, researchers at the Massachusetts Institute of Technology administered the probiotic Lactobacillus reuteri to mice and measured what they termed ‘the glow of health’—essentially how thick and lustrous their fur and skin were. They noted a visible improvement. Not only that, but they recorded a reduction in inflammation and signs of repair in both the barriers of the skin and the gut.

A Two-Pronged Attack
Two months on, and there’s little change in the state of my skin. It’s not that I think Louch’s approach isn’t working—she warns it will be at least four months until I see any difference—but the more I understand my gut, the more I think I might need to go a little ninja on it.

So I arrange to see Hannah Richards, a diagnostic nutritionist and co-founder of wellness company Move Three Sixty. She goes one better than Louch and asks me to provide a stool sample—the bacteria found in your, er, poo are representative of the bacteria present in your gastrointestinal tract. So there’s now a lab-coated individual in Arizona learning things about my gut in ways I’d prefer not to contemplate. “It’ll give us a full picture of any parasites or fungal infections that may have taken hold, so we can choose the most effective treatment,” she says. It’s not a cheap option. Sending a sample off to PCI, the lab Richards uses, costs around $300.

Is the investment worth it? When it comes to microbiota, how bespoke can you go? “Gut microbiota differ depending on a range of environmental factors like geography, diet, and lifestyle," says Liu. “But leading researchers who’ve studied the gut profiles of healthy individuals from all over the world have found that there is a core profile that tends to be the same in healthy individuals. We specifically know that in acne cases there are a couple of bad bacteria, like Corynebacterium, that are often out of balance. I suggest people get tested so we know the extent of the dysbiosis [imbalance] and tweak accordingly.”

My results show a shockingly low concentration of good bacteria. We have to wait for further analysis to find out which bad stuff has gotten out of control (happily, I'm parasite-free), but taking my symptoms and Louch's diagnosis into account, Richards suggests a complete probiotic, as well as a regimen of pills containing antibacterials like garlic, ginger, and oregano oil. She suspects it will take at least six months for me to get anywhere near balanced.

Of course, the other part of this is food—probiotics aren’t going to do much if you’re living on coffee, cake, and KFC. One recent study by Tim Spector, a professor of genetic epidemiology at King’s College London, found that just 10 days eating junk food reduced microbiota diversity by a third. “Pathogens love sugar and processed carbs, so you need stay away from both,” says Richards. She refuses to say "cut out completely." She’s a realist, and she’s already clocked the frustration of someone who’s spent years on-and-off cutting out entire food groups and significant amounts of fun in the process. “I know that you’ve tried all of these diets, and yes, they may have worked for a time, but the problem is you’ve never fixed the underlying problem with your gut," she says. "The pathogens effectively go into hiding, but as soon as you start eating sugar again, it’s like feeding time at the zoo and your symptoms will flair up. Fix the gut, get your bacteria in balance and the pathogens won’t have the space to flourish.”

She only puts in one strict rule: no dairy. “Both dairy and gluten can open gateways in the gut wall increasing permeability,” says Liu. “If your gut is strong enough and you don’t have a specific intolerance, then it should be able to resist, but while you’re fixing a gut, I’d definitely stay away from both."

It’s all about vegetables. They’re teeming with the sort of living microorganisms that nourish the gut—which brings us to prebiotic foods. "They are a type of fiber that reach the colon intact and feed the good bacteria," says Liu. "I recommend getting more cooked resistance starch. This is produced when starchy foods like potatoes and brown rice are cooked then cooled. Next, there’s a particularly clever sort of fiber called oligosaccharides. You’ll find these in chicory root, Jerusalem artichokes, garlic, onions, and legumes like lentils and chickpeas. When the gut microbiota feed on both of these, they produce short-chain fatty acids, which improve gut health and have been shown to play a part in decreasing inflammation.

People with gut or skin problems often cut out carbs completely, but I’m not sure going Paleo is always the best answer. Eating at least 30 grams of fiber every day helps."

And if you haven’t got on the fermented foods bandwagon, it’s time. "Foods like sauerkraut, kombucha, and kimchi are probiotic powerhouses that will nourish the bacteria in your gut,” says Richards, “so aim for a serving a day."

And so this is where I am now—spooning sauerkraut on my lunchtime salad. I am not expecting miracles, and right now, two days before my period is due, I’m getting a familiar spattering of spots along my jawline. As Bowe says: “There are numerous contributing factors to all skin conditions, and you can’t just sit at home, pop a probiotic and expect your skin to clear up. But it’s a significant piece of the jigsaw. One that you just can’t ignore.”